Volts, Amps, Ohms and calculation
see French version
Source: Pratique de l'électiricté moto, D. Dubois, ed ETAI

Increased resistance
Increased resistance (see Ohms law) for a constant voltage lowers the number of Watts used by a device, resulting in a non operating bulb or..
Two things increase ressistance in a circuit : oxydation and cold.
Source: Pratique de l'électiricté moto, D. Dubois, ed ETAI